Energy-summed waveforms (left) and phase-summed spectra (right) for the Ring-Eq case. The bottom subpanels show the fractional difference (in %) of each configuration relative to the X-PSI Ultra-resolution benchmark (black dotted). CPU results are plotted with solid lines: standard resolution (blue solid) and high resolution (red solid). GPU results are plotted with dashed lines: standard resolution (blue dashed) and high resolution (red dashed). In the left panel, the legend reports χ² as defined in Equation (57), computed jointly over energy and phase channels as a quantitative measure of the discrepancy between full energy-resolved pulse profile. In the right panel, the legend lists the runtime for each configuration. Gray dashed lines in the bottom subpanels indicate the expected Poisson fluctuations of the Ultra-resolution X-PSI benchmark.